Gear structure



Patented API. 21, 1936 UNITED STATES PATENT OFFICE GEAR. STRUCTURE Application May 15, 1933, Serial No. 671,124

4 Claims.

This invention relates to gear structures and particularly to the construction of relatively large gears.

An object of the present invention is to provide 5 a relatively large, accurately centered, and accurately balanced. gear, so constructed as to provide adequate strength and rigidty with minimum weight.

Large gears, several feet in diameter, are not uncommonly employed as propeller shaft drives in marine installations. Their size and rate of operation is such as to require accurate centering and accurate balancing, to etfect a smooth gear action and avoid objectionable vibration,

and, in order to facilitate maneuvering, it is highly desirable that the weight of such gears be reduced to a minimum consistent with strength and rigidity. In the gear of the present invention, all ci these desirable characteristics are developed to a high degree.

Other objects and advantages will appear, expressed or implied, from the following description of a gear embodying the present invention.

The single figure of the accompanying drawing is a view, partly in section, and partly in elevation, of a larga cast steel gear constructed. in accordance with the present invention.

The gear shown is of the double helical type. It includes two concentric, axally spaced rims I 0 of the same diameter, having oppositely inclined helical teeth out therein. The rims IO are connected. through a rigicl box like formation, including an ntermediate, concentric, cylindrical web Il of lesser-diameter, having integral external end rings I2 which merge into the rims adiacent their inner edges. The gear is internally braced. against distortion by a concentric substantially conical web 13, whose large end merges into the web Il, preferably at one end thereof, and which slopes inwardly therefrom into an end zone of the gear.

The gear is supported and centered primarly by a pair of end dsks I and l5, closely fitted ai; their peripheres against accurately machined internal shoulders l6 and I i, formecl adjacent the outer edges of the rims IO, and bored to seat upon machined shoulders l8 and l9, formed upon integra] collars 20 and 2|, provided. on the shaft 22. The end. disks are attached. by bolting or otherwise to internal flanges 23 and 24, formed in the rims IO, and also to the shaft collars 20 and 21. The small end of the conical web l3 is also bored to seat snugly upon a machined. shoulder 25 on the shaft collar 20 to which it is similarly attached.

It will thus be noted that a gear structure has been provided in which all of the parts may be of unusually thin, light weight design, without impairing the strength and rigidity of the gear structure, and in which both the internal and 5 external surfaces of all of the parts are easily accessible and can thus be readily and accurately machined, by ordinary shop methods, to obtain any desired thinness of the several parts and to eiect an accurately balanced gear.

In producing the gear shown, the rims IO, web Il, rings I2, and web 13 are cast in one integral piece in which all of the parts are of a thickness consistent with goocl foundry practice. The external and internal surfaces of the blank are then machined to greatly reduce the several parts to the desired thnness and to effect an accurately balanced gear blank, and the blank is finally assembled with the previously finished. end disks M and I 5 mounted upon the shaft 22, in the manner indicated.

Various changes may be made in the embodment of the invention hereinabove sbecifically described without departing from or sacrificing the aclvantages of the invention as hereinafter claimecl.

Wc claimz- 1. A large marine gear structure comprising the combnation of-a pair of concentric axially spaced rims having teeth formed thereon, an intermediate concentric web connecting said rims, and a concentric conical brace structure extendng from said web toward an end zone of the gear, said rims, web, and brace structure comprising a one piece casting all of the internal surfaces of which are accessible for machining to reduce the thickness thereof and to balance the gear, together with a pair of end disks engaged. with said rims adjacent their outer edges to support and center the same, and rigid mounting means for said disks and brace member.

2. A large marine gear structure comprisirig the combination of a pair of concentric axially spaced rims having teeth formed thereon, a concentric cylindrical web having external end rings connected with said. rims adjacent the inner ends thereof, and a concentric conical web extending from an end of said cylindrical web into an end zone of the gear, saiol rims, rings, and webs comprising a one piece casting having internal surfaces accessible for machining to reduce the thickness thereof and to balance the gear, together with a pair of disks engaged. within said rims to support and center the same, and a shaft on which sad dsks and. conical web are mounted end secured.

3. A large marine gear blank comprisng a pair of concentric axia.lly spaced tooth carrying rms, a, concentrc web structure Wthin said rms and having a. tapered. end, and spaced rings connecting said Web structure With said rims, said. rims, rngs, and web structure comprsng a, one piece casting all of the internal surfaces of which are accessible for machnng to reduce the thickness of said parts and to balance the gear.

4. A large marine gear comprsing the combination of an axially extended. rm structure ha.vng two series of oppositely nclined helical gear said dsks and brace member to support and brace 10 the gear.

HAROLD S. FALK. PERCY C. DAY. 

